We broke the tomato, and we’re using science to fix it

We've bred tomatoes for high productivity with no regard for their taste.

Thanks to decades of breeding, the modern agricultural tomato has a lot of properties that are great for farmers: the plants are incredibly productive, and the resulting tomatoes hold up well to shipping. Just one small problem: they are nearly tasteless. Heirloom tomato strains have become available precisely because people aren't especially interested in the mass-produced, modern tomato.

In the words of a panel at the meeting of the American Association for the Advancement of science, we "broke" the tomato by allowing the plant breeders to respond to the needs of farmers, instead of the tomato's end-users: consumers. As a result, their breeding has produced a product that most people don't actually enjoy eating. And that's a public health issue, given that tomato-rich diets have been associated with a variety of beneficial effects.

Fortunately, the panel featured a number of people who are trying to fix the tomato using up-to-date biochemistry and genetics.

Yale's Linda Bartoshuk set up the challenge with a little experiment: everyone in the audience was given a raspberry Jelly Belly. Bartoshuk had people hold their nose, then start chewing on the candy. For me, it tasted generically sweet. When, on her instructions, I released my finger, there was a sudden explosion of flavor, a lot of it evocative of raspberries—and a sudden murmur from the audience suggesting they were experiencing something similar.

What's going on? A lot of our experience of flavor really does come from smell, but not from breathing in; instead, volatile chemicals disperse out of the back of your mouth, with some of them reaching your nasal passages. Not only can these volatiles convey a distinctive flavor, but they can also interact with flavors sensed by the tongue, enhancing or suppressing sweetness, saltiness, etc.

Harry Klee of the University of Florida has put together a collection of over 200 tomatoes, some heirloom, some the mainstream agricultural strains. Using those, his team has characterized the volatile chemicals present in each, coming up with a list of about 68. They've also put about 100 of those tomatoes to the test with a panel of tasters, who rated their appeal and flavor. (One of the things he discovered is that some heirloom strains are "really not very good.")

The result is that the team has what you might consider a statistical recipe for a good tomato. Generally, what consumers like is perceived sweetness (though other factors also played in, like saltiness and tartness). And in general, the perceived sweetness was roughly in line with the amount of sugar present. But only roughly. Klee pointed out two varieties (Matina and Yellow Jelly Bean) that had similar levels of sugar, but one was perceived as twice as sweet as the other—the one with slightly less sugar.

The difference: the concentration of various volatiles in the tomatoes which are quite often derivatives of carotenoids, chemicals most closely associated with carrots. The derivatives were considered fruity and floral, and were correlated with both perceived sweetness and likability. Fortunately, the pathways that convert the carotenoids into these derivates are fairly well understood, and the authors leveraged some genetics. Tomatoes with knockouts of the genes involved in creating these derivatives were tested with consumers, and these confirmed that the resulting fruit were rated as lower sweetness.

Klee's team has started identifying alleles that enable production of a variety of volatiles in heirloom strains, and started introducing them into high production commercial strains. According to him, a single cross can give heirloom flavor with double the yield of the original heirloom strain—not enough to get commercial growers to switch, but a step in the right direction. Further breeding and, if necessary, some genetic engineering may return the heirloom genes, along with some taste, to the modern tomato.

127 Reader Comments

Its anecdotal, but the few food company "chefs" I have met are all chemical engineers.

I do not know why this suprises you, most of the top chefs in the world right now are heavily into chemistry if not having a background in chemistry. What do you think causes flavor in the first place? Here is some background info for you:

I'm heavily into cooking, and I tend to follow the latest developments. Its tough to be a chef nowadays without some knowledge of chemistry, and the ones who actually are chemists have a massive edge.

A massive edge over what?

Any chef not using a knowledge of chemistry to inform their skill.

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And to accomplish what?

Make better tasting food. By understanding how the molecules of that food react with each other and temperature in specific amounts.

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There are heaps of chefs who simply have fantastic instincts, or who have studied traditions and consequently experimented with them without necessarily cracking a Harold McGee tome. Guess I don't understand what your "edge" refers to.

Those chefs are embracing chemistry too because it makes what they do better and easier to replicate. If you do not understand why something works, replicating it reliably is extremely challenging. Molecular gastronomy is turning food preparation into a science, and that is a good thing.

I would be shocked if there was a single top rated chef these days who was not using at the least knowledge of temperature control in their cooking. That is one of the fundamentals of the practice. There is a reason you do not simply turn everything on 'high' and toss it all together. All that is happening now is that knowledge is being formalized, reasons why are being understood, and results are being replicated.

You really showed you scientific knowledge with that post. Prions are not pathogens. Pathogens are organisms. Prions are misfolded proteins. Pathogens can be killed with heat and are the reason why we cook our food. Prions, like the one for MCD, can not be destroyed by cooking. (incineration is not cooking) Hence the reason why MCD disease is hard to stop. MCD has little to do with GM crops other than they are the result of stupid human behavior.

I just want to point out that prions are considered pathogens by many. Its listed as a pathogen in the Wikipedia entry and in prionic theory.

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Also, there are no regulations regarding clinical trials for GM crops. Only a rough risk assessment. A guess.

This is patently false. Citation needed.

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The problem with GM crops is that they are formed from taking DNA from a virus. Then the genes are basically smashed into the crop DNA. Problem is that viruses tend to mutate quite a lot. How long until there is a mishap and the wrong genes gets introduced to the crop? Or worse, the genes we are moving start doing something other than what they used to do. It tends to take a long time for us humans to realize some of our mistakes (DDT?). Since we are already over producing for our needs, why take the risks?

Why aren't they running human clinical trials? They assumed that the new crops were safe since the non modified ones were. So they did a risk assessment and made a guess.

As for risk, doing anything to change the food is riskier than doing nothing to it. That's just a matter of logic. It may be a very small risk. But since we produce more food than we need, why take ANY risk?

1) These products are global and there are often restrictions in other nations.2) The US actually does control GMO's and review them before release. A quick glance at Wikipedia finds this section with references: http://en.wikipedia.org/wiki/Regulation ... th_America3) Why would you mandate human trials and what would you be looking for? What do you expect it to prove or disprove? And what would the baseline be for comparison?

Finally, as for risk, your assertion that doing anything to change food is riskier than doing nothing, all I can say is that we have been changing food in a uncontrolled fashion for more than ten thousand years. GMO's permit us to make those changes in a controlled fashion, which actually is a huge mitigation of risk. In the past, for instance, farmers would breed potatoes in order to have just enough nightshade to repel pests, but not enough to harm humans. It was risky, and it was not unheard of for a random potato to kill someone. Now with GMO methods we can make certain that every crop we add the gene to the amount of nightshade is safe for human consumption, but reduces the ability of pests to harm the crop, which in turn reduces our use of pesticide. Its a win all around.

GMO is a huge tool in the improvement of the food chain, from a cost, environmental impact and human safety point of view.

Like most people here, I was shocked the first time I ate "real" tomatoes. I had no idea tomatoes could have that much flavour. The side effect was that I started avoiding standard supermarket tomatoes, which resulted in me eating less tomatoes altogether. So in that sense, maybe I'm worse off for knowing how tomatoes ought to taste. However, if we want to encourage people to consume more fruits and vegetables in their diet, having better tasting ones would be a good start. Another poster mentioned the premium cultivar system used with apples. I think it's great. I gladly pay more for Honeycrisp apples and I would do the same for other fruits/vegetables.

Being careless about plant breeding in the past does not excuse doing it now. It was slow and took thousands of years and we were able to absorb the information as we made changes. The changes we are making now with GMO are not being studied enough before being introduced to the food chain.

I would think that at some point we would study the long term affect of these plants on humans and the environment. Why is it that the soap I use and wash off with goes through more clinical trials that the corn in my cereal? Also, should the company that stands to make a fortune really be the end point for real safety discussions?

Monsanto states: "There is no need to test the safety of DNA introduced into GM crops. DNA (and resulting RNA) is present in almost all foods--the only exceptions being highly refined materials like oil or sugar from which all cell material has been removed. Thus, DNA is non-toxic and the presence of DNA, in and of itself, presents no hazard. " Yet you yourself point out how people used to die from breeding too much nightshade into potatoes.

GMO may be the best thing to happen to humans in years. Then again, it may be the next DDT. Tobacco used to be good for you too. I would just like some independent testing done before we all start eating these new species.

Being careless about plant breeding in the past does not excuse doing it now. It was slow and took thousands of years and we were able to absorb the information as we made changes. The changes we are making now with GMO are not being studied enough before being introduced to the food chain.

I would think that at some point we would study the long term affect of these plants on humans and the environment. Why is it that the soap I use and wash off with goes through more clinical trials that the corn in my cereal?

Citation needed. Both genetically modified organisms and soaps are tested. However, neither of these involve "clinical trials". Toxicity testing is done in animals.

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Also, should the company that stands to make a fortune really be the end point for real safety discussions?

Yes. Who else is going to pay the costs? If a product is toxic, who is going to pay the legal costs other than the company involved (and the plaintiffs)?

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Monsanto states: "There is no need to test the safety of DNA introduced into GM crops. DNA (and resulting RNA) is present in almost all foods--the only exceptions being highly refined materials like oil or sugar from which all cell material has been removed. Thus, DNA is non-toxic and the presence of DNA, in and of itself, presents no hazard. " Yet you yourself point out how people used to die from breeding too much nightshade into potatoes.

You are failing to differentiate between the genetic material and the gene product.

Atropine is toxic. The DNA (and resulting RNA) involved are not toxic, nor are the enzymes involved in the atropine synthesis pathway. Testing for the results of the modification are likely to be all that is necessary.

(Note: it is clearly possible to make a toxic organism using genetic engineering. Arguably, BT-containing organisms fall into this category, although only for the insects that eat those organisms. However, the companies making genetically modified food plants are aware of the consequences that would result from incorporation of human toxins into food plants, intentionally or inadvertently, and are highly unlikely to risk any such action.)

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GMO may be the best thing to happen to humans in years. Then again, it may be the next DDT. Tobacco used to be good for you too. I would just like some independent testing done before we all start eating these new species.

Tobacco was never "good for you"; even before the link to cancer became unquestionable, people were aware of some of its deleterious effects. I have seen no clinical trials on tobacco use in humans that showed any sort of benefit to the user.

As for the "independent testing" -- who is going to pay for the tests? And, who would you consider to be "independent"?

Being careless about plant breeding in the past does not excuse doing it now. It was slow and took thousands of years and we were able to absorb the information as we made changes. The changes we are making now with GMO are not being studied enough before being introduced to the food chain.

What would you consider to be enough study? And on what data points are you basing that estimation? Should I remind you that we've been GMO'ing food directly for four decades now without any issues traced to that work? And that as a species we have been crossbreeding, selectively breeding and hybridizing our food supply for more than ten thousand years? And that the process of creating and improving our food supply has only gotten safer over time, not more dangerous?

At what point does track record actually count for something?

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I would think that at some point we would study the long term affect of these plants on humans and the environment. Why is it that the soap I use and wash off with goes through more clinical trials that the corn in my cereal? Also, should the company that stands to make a fortune really be the end point for real safety discussions?

As pointed out above, soap does not go through clinical trials either. Only drugs do. But the question I have is why do you assume that long term effects are not being studied now? Furthermore, why do you not think that negative side effects would not already have been detected given that people in their 30's have been living with a high level of GMO's their entire lives?

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Monsanto states: "There is no need to test the safety of DNA introduced into GM crops. DNA (and resulting RNA) is present in almost all foods--the only exceptions being highly refined materials like oil or sugar from which all cell material has been removed. Thus, DNA is non-toxic and the presence of DNA, in and of itself, presents no hazard. " Yet you yourself point out how people used to die from breeding too much nightshade into potatoes.

What is factually incorrect about Monsanto's statement? And how does it relate to the fact that our previous method of producing ideal food was more dangerous than what we are doing today, which was why I pointed out that potatoes used to kill but now do not.

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GMO may be the best thing to happen to humans in years. Then again, it may be the next DDT. Tobacco used to be good for you too. I would just like some independent testing done before we all start eating these new species.

GMO already happened. It happened decades ago. Nothing bad has come of it. In fact, food safety is higher than ever. And you are already eating them and likely have been your entire life.

Not sure what you mean about tobacco. It was used in the past as a treatment for some things, but I am not aware of any scientific research that ever declared it 'beneficial' for routine consumption.

As someone who has grown tomatoes for many years at home...there are some things that will make your tomatoes even better.1. Soil Soil Soil!!! Tomatoes are heavy feeders and like a nice nitrogen/potassium rich soil. If you compost thats the best thing you can do for your soil.2. Plant beans where you planted tomatoes last year if you have the room. Many varieties of beans actually ADD nutrients to the soil.3. Never plant tomatoe plants in exactly the same location every year or you are just asking for tomatoe malware (bad insects, wilt, and other disease) which can and do overwinter in the soil. If you live in a climate where you get hard freezes, it can be very beneficial if you turn the soil mid winter or before the last freeze to get some of the critters that are hiding just waiting to do damage when its warm again.

Some of my favorites are pink heirlooms (sweetness), the yellow varieties (not as acidic), Romas (good for making sun-dried which you can keep for long periods of time), and of course the Big Beefsteak varieties (sliced with a little balsamic vinegar and some good mozzerella on top under a broiler for a minute or two until brown...who cant do that!). Also look for disease resistant varieties. Heirlooms may sound good but can be challenging to grow as they are not very disease resistent.

I know I'm really late to the party, but all the GMO discussion is pointless. We can breed these important flavors back into your standard tomato without the need for GMO.

The thing about tomato is that there is a threshold of sugars (Suc, Fru, Glu) that need to be met for basic quality, but further increases in sugar are hard to do without significant losses in yield. There are tests that suggest that you need an ~25% increase in sugars for a consumer to detect the change beyond that initial threshold. The amount of carbon needed for this increase is massive (measured in g/100g), but for a similar detectable increase in "sweetness" via volatiles would be (µg/100g). The leftover carbon could go into other fruit for high yield.

I really think that Linda, Harry, and Monsanto are milking this a bit though. They've not really published much that is new recently and yet they are hitting the circuit pretty hard lately.

John, did they do the bitter test with the little pieces of paper? I think the interaction between the consumer's ability to taste and the flavor components of our food are pretty darn interesting.

Conflicts of Interest: UF graduate and currently employed by Seed Industry.